Deicing means for airplanes



g-" 39 YW.S.DIEHL. 2,168,328

DEICING MEANS FOR AIRPLANES Filed Dec z. 4, 1937 I IIIIIIIIII/IIII/IIIIIIIIIII INVENTOR F 5 BY WALTER s. QIEHL a /K 2 ATTORNEY n ing conditions.

Patented Aug. 8, 1939 {PATENT OFFICE I marcmc -MEANS FOR. AIRPLANES Walter S. Dielil, United States Navy Application December 4, 1937, Serial No. 178,095

6 Claims.

I (Granted under the act of March 3, 1883, as

amended April 30, 1928; 370 0. G. 757) This invention relates to devices for preventing accumulation of ice upon airplanes or the like, and more particularly to the types of deicing means employing elastic coverings on the 5 leading edges of airfoils.

Heretofore, rubber sheeting, rubberized fabricated sheeting and the like, have been used as covers or overshoes on the leading edges of surfaces of airplanes that are exposed to ice form- Certain portions of these covers or overshoes were inflatable so as to break up the formations of ice, which are then removed by the force of the air stream. However, trouble has been encountered, especially at high speeds, due to the area of negative pressure produced by the airfoil. This causes the sheeting to lift away from the surface of the airfoil and results in a flapping of the portion of the overshoe between the inflatable tubes and the line at which the overshoe is fastened to the surface of the airfoil. This undesirable movement of the overshoe adversely affects the airfoil properties and sets up vibrations within the structure.

Gne of the objects of the present invention is to avoid any flapping of the overshoe by equalizing the pressure on the under surface of th sheeting with that on its outer surface. Another object of the invention is to provide means for more positively holding the sheeting against the airfoil surface, by so constructing the overshoe that a greater negative pressure will be present on the under surface of the overshoe than on its outer surface.

A further object of the invention is to obtain a lesser pressure on the overshoes under surface by a source other than the construction of the overshoe itself. I

With such objects in view, as well as other advantages which may be incidentto the use of 40 the improvements, the invention consists of the parts and combinations thereof hereinafter set forth and claimed, with the understanding that the several necessary elements constituting the same may be varied in proportion and arrange- 45 ment without departing from the nature and scope of the invention as defined in the appended claims.

In order to make the invention more clearly understood there are shown in the accompany- 50 ing drawing means for carrying the invention into practical effect, without limiting the improvements in their useful application, which for purpose of explanation have been'made the subject of illustration.

55 In the accompanying drawing:

Figure 1 is a section through the leading edge of an airfoil provided with an elastic sheeting or overshoe constructed in accordance with the present invention.

Figures 2 and 2A are plan views of Figure 1. 5 Figures 3 and 4 are sectional views of other forms of my invention.

Referring to the drawing, in Figure 1 the framework II) and covering H of an airfoil are shown. The leading edge of the airfoil is provided with an elastic overshoe I2, attached at its boundaries to the covering I Lin any well known manner, such as riveting, cementing, vulcanizingor lacing. The elastic. overshoe I2 is provided with a plurality of longitudinal slots or tubes I3 which may be intermittently inflated in manners well known in the art. The swelling of the slots or tubes I3 serves the purpose of breaking up or preventing the formation of ice on the airfoil. 20

In order to prevent flapping of the elastic overshoe I 2, I have introduced a series of apertures I4 between the outer and under surfaces of the overshoe I2. Equalization of the pressure on the two surfaces of the overshoe I2 takes place 25 through the apertures I I.

Complete relief of the pressure requires reasonably free passage of air under the elastic overshoe I2. This is obtained by a plurality of 3 knobs I5 or broken ridges I6. Figure 2 illustrates one pattern in which such knobs I5 may be arranged, while Figure 2A similarly'shows one pattern or broken ridges I6. The knobs I5, broken ridges I6, or any other form of protuberances, or combinations thereof, may be arranged in any desiredpattern. The protuberances are so spaced relative to the thickness of the overshoe I2, the tension, and the pressure difference, that the intermediate panels of the overshoe I2 will not collapse and thereby act as valves 40 against the remaining area. A

A modification of myinvention as hereinabove described is illustrated in Figure 3. Slight protuberances I! are provided on the outer surface of the overshoe I2 about the apertures I4. These protuberances Il may be of any desired shape such as a portion of a sphere, an approximate half-streamline, ora half-ellipsoid. They increase the thickness of the overshoe I2 by an amount that will insure the mouths of the apertures I4 being above the remaining surface of the overshoe I2 even in the event of the overshoe I2 collapsing to the covering I I between the knobs I5 or broken ridges I6. The protuberances I1, 55

being small, donot increase the drag due to the leading edge covering nor spoil the lift. The

- local increase in air velocity over the top of the protuberances I 1 produces an increased suction which is transmitted through the apertures H to the under surface of the overshoe l2, thus holding the sheeting tighter to the covering ll ,of the airfoil as the speed increases.

. factured and used by or for In Figure 4 another form of my invention is shown. The elastic overshoe I2 is provided with inflatable slots or tubes l3 and a pattern of knobs l5 or broken ridges l6 hereinabove described. the overshoe l2 tightly Suction which will hold against the covering H of the "airfoil is obtained from an outside source by connecting a series of pipes or tubes IE to the area under the overshoe l2. These pipes or tubes l8 are spaced in the same manner as the apertures ll of the other embodiments of this invention. The source of the suction transmitted by the pipes l8 may be a Venturi tube IS in the air stream as.illustrated, or any other low pressure source such as avacuum pump or a Venturi tube in the engine exhaust.

The herein described invention may be manuthe Government of the United States of America for governmental purposes, without the payment of any royalties thereon.

I claim: 1. A deicing means for airplane sufaces exposed to ice-forming conditions comprising an expanmeans for producing sible elastic covering secured to such surface and a lesser pressure on the inner surface of said overing than on the outer surface thereof. f

2. A deicing means for airplane surfaces exposedto ice-forming conditions comprising an expansible elastic covering secured to such suron its under surface as face, said covering having a plurality of protuber ances on the outer surface thereof, each of said protuberances having an aperture extending through the covering to permit air pressure to equalize on the inner surface thereof.

3. A deicing means for airplane surfaces exposed to ice-forming conditions comprisinga'n expansible elastic covering secured to such surface, said covering having a plurality of protuberances on the outer surface thereof, each of said protuberances having an aperture extending through the covering to permit air pressure to equalize on the inner surface thereof and a plurality of protuberances on the inner surface of said covering for maintaining said covering in spaced relation to the surface to which it is secured. L

4. A deicing means for airplane surfaces exposed to ice-forming conditions comprising an expansible elastic covering secured to such surface, and means connected with the space between said covering and the surface to which it is secured for reducing the air pressure in said space below that on the outer surface of said covering.

5. A deicing means for airplane surfaces exposed to ice-forming conditions comprising an expansible elastic covering secured to such sur-' face and means located in an area of relatively low air pressure for lowering the air pressure on the inner surface of said covering.

-6. A deicing means for airplane surfaces exposed to ice-forming conditions comprising an expansible elastic covering secured to such surface, and venturi means located in the slip stream of the airplane and connected with the space between said covering and the surface to which it is secured for reducing the air pressure on the inner surface of said covering.

WALTER S. DIEHL. 

